On a coordinate plane, a graph has number of inches on the x-axis and number of miles on the y-axis. A line goes through points (2, 10), (4, 20), and (5, 25). The graph shows the relationship between inches, x, and miles, y, on a map. Which equation represents the proportional relationship? y = x + 5
y = one-fifth x
y = 5x
y = 10x